First repeated character

Author: anantkaushik

Google/Problem#649.py

@@ -0,0 +1,14 @@
+"""
+Given a string, return the first recurring character in it, or null if there is no recurring character.
+For example, given the string "acbbac", return "b". Given the string "abcdef", return null.
+"""
+def firstRepeatedChar(s):
+    
+    alphabets = set()
+    
+    for c in s:
+      if c in alphabets:
+          return c
+      alphabets.add(c)
+    
+    return None